William Jackson seaskiff stretch

As Tops noted you are proposing 24% stretch. As Gonzo says, the lateral stability will increase, but only if the draft of the longer boat is the same as the draft of the 13 foot nine inch boat...........

Bill Jackson designed a lot of little boats whose plans were published in Old time magazines like Popular Mechanics, How to Build 20 boats , and others.. That was way back in the 1950s and 1960s. The Sea Squirt plan set is certainly cheap but not a good bargain.

The sea squirt is not the best design to use if you want a boat a little more up to date in terms of design and construction detail. Your Best bet is to buy a set of plans that is of a more current creation. You will spend perfectly good money for materials and also spend a lot of time for the build along with the skinned knuckles and the probable use of impolite words, no matter which boat you build. So why not build a proven design for a seventeen footer? Duck Works, Glen L and several other sources have proven plans.

I'll bet a chicken dinner that the finished cost of your boat will be less if you buy a good set of plans from an established supplier.

 

*ties another square float right of the center line weighing 1000 lbs*

 

What do you mean?

 

Just finding an edge case.
Your example says to join two squares to each other and previous comments say it should be the same height and width. But it didn't say anything about weight and and where to join the two squares. So if I were to join a second heavier square off center from the first, the model would now be listing even without any load.

 

To the promoters: thank you.

To those urging caution, thank you and I get it.

Here’s the thing, I’m well aware this thing might not sit on its lines well without me carefully adding ballast, particularly around the centerboard. I’ve built 8 boats, including shortening a design, and two one offs I figured out myself, both were decent. All were made with cheap materials and semi disposable.

The reason for the fixation with the sea skiff is the v hull, the jig, and the fact that I had cut the side panels for a Redmond bluegill skiff. The cut panels for the bluegill will cover the sides (with a little bit of an extension).

 

OK Murky Deep. Inasmuch as you are an experienced builder, I say go for it.

Much of the time an OP is a rank amateur with misconceptions about the time, money, and patience that is required to build a boat that satisfies his or her desires. In those cases we old timers usually try to offer polite advice based on our own long term experience.

 

I was just intentionally misunderstanding Gonzo's example as a joke. Do you post pictures of your finished builds?

 

Thanks @Murky Deep, the additional details about your previous designs and builds... these with desired hull form, build method, and materials on-hand make the project more clear. At this point I would ask if you need the 17', could you go say 15' & change and not need to add to the Bluegill panels?

 

Also, what I’d build if the plans were available-note the similarities.

 

STOP!!!
Fullstop!

 

Stop!!! Full stop!

 

Stretching a plan by 10% usually works.
2 1/2 times that and randomly beefed up scantlings means you need to step back and find a design better matched to your needs.
I've built enough boats to know when I'm headed the wrong direction. Still, I had a close call with the wrong hull five years ago. IMO you are in over your head, stop digging.

 

The 10% rule of thumb is not for stretching, but for scaling up or down all dimensions.

 

I could probably deal with 15’, it’s just that an extra couple feet goes a long way towards space for easy fishing.

 

On a 15' the trout I catch usually overhangs. I feel you man.